Mobile communication system using a downlink shared channel

ABSTRACT

A system for mobile communication includes a base station and a mobile station. The base station includes a first transmitting unit operable to transmit to a mobile station, identifying information for multicast data to be to the mobile station, and a second transmitting unit operable to transmit the data on a shared channel to the mobile station, wherein the data is identified by the information transmitted. The mobile station includes a first receiving unit operable to receive from the base station identifying information for the multicast data, and a second receiving unit operable to receive the data on the shared channel from the base station, by the information received.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/999,206, filed Nov. 24, 2004, which is a continuation ofInternational Application No. PCT/JP02/05340, filed May 31, 2002, whichare hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a communication method and device in amobile communication system using a downlink shared channel (DSCH).

BACKGROUND ART

In recent years, development of CDMA (Code Division Multiple Access)communication systems has proceeded apace, and the need to shift toWideband-CDMA (W-CDMA) systems that provide a wider bandwidth thanpreviously in order to exchange not merely voice but also large-capacitydata such as images or video at high speed, and with high quality andefficiency has increased.

Communication systems adapted to these demands are generally calledthird generation mobile communication systems and the standards relatingthereto are co-coordinated by the 3GPP (Third Generation PartnershipProject), which is the world standardization organization; introductionof such systems has already begun.

In 3GPP, a DSCH (downlink shared channel) is defined as a downlinkchannel that is used in shared fashion by a plurality of mobiles (see3GPP TS 25.427, TS 25.435). With DSCH, a single channel can be shared bya large number of mobiles and flexible power control can be achieved. Inthis way, high-speed and high-efficiency data communication can beimplemented with limited wireless resources so the importance of thistechnique is expected to increase in the future.

FIG. 1A to 1C show an outline of downlink data communication(communication to mobiles) in a communication system employing DSCH.This system comprises a core network 100, which is a wired network, awireless network control device 101, base stations 102 and mobiles 103.

DSCH is the name given to the channel between the wireless networkcontrol device 101 and the base stations 102; this DSCH is mapped onto aPDSCH (physical downlink shared channel), which is one of the physicalchannels on wireless.

Also, for a single mobile 103, there is a single individually assignedchannel, which is called a dedicated channel (DCH) between the wirelessnetwork control device 101 and a base station 102, and which is called adedicated physical channel (DPCH) on wireless. The mapping of thechannels is defined in 3GPP TS 25.301.

As shown in FIG. 1A, when data is transmitted on a DSCH, it is necessaryto transmit control data, called signaling, on the DPCH. The signalingdata is used to report to the mobile 103 whether or not data is presenton the PDSCH, at a timing corresponding to this signaling.

Specifically, the mobile 103 is not always in receiving condition inregard to the PDSCH but only receives data on the PDSCH if signalingdata has been received on the DPCH.

The ability to receive data on the DSCH therefore only exists in thecase where a dedicated CH is set up in respect of the mobile 103; datacannot be received on the DSCH in the idle state or in a condition inwhich a dedicated channel is not set up. It should be noted that themobile 103 is normally able to receive signaling data on the DPCH.

Mapping of the aforesaid signaling data wirelessly onto DPCH is asdescribed above. Two methods are laid down between the wireless networkcontrol device 101 and base station 102. In one case, data istransmitted on. DCH. In the other case, data is transmitted on anotherchannel established for the signaling.

Thereupon, after the mobile 103 has received the signaling data, inorder to start preparation for receiving the DSCH, the DSCH data must betransmitted later than the signaling by a delay time ΔT.

The DSCH data is transmitted in accordance with a standard timing thatis set for each sector, so the reception timings thereof are the samefor the mobiles 103. In contrast, the DPCH reception timings aredifferent for each of the mobiles 103. Consequently, the aforesaid delaytime ΔT also differs for each mobile 103. The wireless network controldevice 101 must therefore perform transmission timing control of thesignaling data, in consideration the delay time ΔT for each mobile 103.

It should be noted that the delay time Δ T is respectively reported tothe wireless network control device 101, base station 102 and mobile 103by the application at the time point of call set-up.

Also, as shown in FIG. 1B, the identifier ID 104-2 that is applied toeach mobile is stored in the DSCH frame 104 in addition to the user data104-1. This is necessary in order that the DSCH frame 104 should becorrectly transmitted to a specified mobile 103.

For this reason, as shown in FIG. 1C, transmission can only be effectedin respect of a single mobile 103 in a single transmission slot; a DSCHframe that is transmitted in this transmission slot cannot besimultaneously received by a plurality of mobiles 103.

FIG. 2 shows an example of the processing sequence in DSCH transmission.When the wireless network control device 101 receives (step S1) userdata 104-1 from the core network 100, it generates a DSCH frame 104(processing step P1) from the information that was already set as theuser data 104-1. After this, the transmission timing of the DSCH frame104 is determined (processing step P2).

Then, after the signaling data has been generated (processing step P3),the transmission timing of the signaling data is determined (processingstep P4) using the aforesaid delay time Δ T, from the DSCH frametransmission timing. The signaling data is transmitted (step S2) to themobile 103 through the base station 102 in accordance with the signalingtransmission timing.

When a mobile 103 receives signaling data, it becomes aware of theexistence of a DSCH frame that is to be received on the PDSCH, andstarts preparation to receive this DSCH frame (processing step P5).After this, the wireless network control device 101 transmits the DSCHframe to the mobile 103 (step S3) through the base station 102 inaccordance with the DSCH frame transmission timing.

After receiving this DSCH frame, the mobile 103 compares the mobileidentifier ID 104-2 in the data with its own ID (processing step P6)and, if they agree, performs subsequent data processing. Also, if themobile ID 104-2 in the DSCH frame data does not agree with its own ID,it discards this DSCH frame (processing step P7).

DISCLOSURE OF THE INVENTION

As described above, since a single DSCH channel is shared by a largenumber of mobiles 103, high-speed/high efficiency wireless communicationcan be achieved. However, as shown in FIG. 1, transmission can only,beeffected in respect of a single mobile 103 in a single transmissionslot. Thus, the DSCH frame that is transmitted in the transmission slot(see FIG. 1C) cannot be simultaneously received by a plurality ofmobiles 103.

In the future, with improvements in transmission rate, it is planned toperfect a large-capacity service providing music delivery and videodelivery, but when DSCH is employed in the current technology, whendistributing the same data to a plurality of mobiles 103 in this way,because of the restrictions described above, it is necessary to transmitexactly the same data to as many mobiles as are to receive it. There istherefore: considerable waste from the point of view of efficiency ofuse of wireless and wired transmission channels and it is thought that,as a result of the accumulation of the amount of data destined for themobiles, the DSCH rate will be adversely affected and communicationquality will tend to be lowered.

Although this problem may apparently be solved by fortifying theinfrastructure, this results in increased costs of the infrastructureand so in increased communication charges and cannot but put a brake onfuture diversification and development of service modes.

An object of the present invention is therefore to provide an efficientcommunication method and device based on the current DSCH technique,whereby diverse services, in particular distribution system services(multi-cast services) can be implemented in future by improvingthe-communication rate.

Furthermore, from the point of view of development costs and developmenttime, it is important to take great pains not to alter-the-existing 3GPPregulations. Also, DSCH has the characteristic feature that reception isonly possible when a dedicated CH has been set up in respect of amobile. In view of this aspect, an object of the present invention is toprovide a communication method and device aimed at implementing furthernew services wherein for example data distribution is performed on DSCHonly during telephone service.

A characteristic feature of a communication method and device accordingto the present invention capable of meeting this object and comprising awireless network control device, base stations and mobiles on whichthere is respectively installed one or more communication protocol asspecified by for example 3GPP is the performance of multi-castcommunication of data in respect of one or more mobiles using DSCH.

In addition, said wireless network control device according to thepresent invention is characterized by the provision of a functionalsection that processes DSCH internally and, in addition, the provisionof table means that stores various types of setting information relatingto DSCH communication and DSCH multi-cast communication. Using theseitems of information, multi-cast communication (including unicastcommunication) is implemented using DSCH in respect of one or moremobiles.

Also, a base station in accordance with the present invention comprisesa function of transmitting DSCH data and/or said signaling data receivedfrom the wireless network control device to the mobiles through awireless circuit.

Furthermore, in addition to the ordinary functions, a mobile maycomprise an identification function in respect of whether data on theDSCH is unicast or multicast.

Further features of the present invention will become clear fromembodiments of the present invention that are described-below withreference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an outline of downlink data communication,(communication to mobiles,) in a communication system employing DSCH.

FIG. 2 is a view showing an example of a processing sequence during DSCHtransmission.

FIG. 3 is a view given in explanation of an outline of a multicast DSCHcommunication method according to the present invention.

FIG. 4 is an operating sequence diagram of the method of multicast DSCHcommunication of FIG. 3.

FIG. 5 is a view showing an embodiment of a wireless network controldevice 303 according to the present invention.

FIG. 6 is a view showing a practical example of a multicast settingtable 502.

FIG. 7 is a view showing a practical example of a DSCH setting table503.

FIG. 8 is a view showing what sort of information is set in themulticast setting table 502.

FIG. 9 is a view showing what sort of information is set in the DSCHsetting table 503.

FIG. 10 is a view showing the correspondence of system state with aspecific example.

FIG. 11 is a view showing the processing sequence from start-up of thesystem up to commencement of multicast communication.

FIG. 12 is a view showing a specific example of a method of signaling.

FIG. 13 is a view showing the processing flow during DSCH transmissionin a wireless network control device 303, in particular a DSCHprocessing section 500 and macro diversity processing section 505.

FIG. 14 is a view showing the processing flow during DSCH reception in amobile.

FIG. 15 is a view given in explanation of the operation when a controlframe is received from a base station 304.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3 is a view given in explanation of an outline of a multicast DSCHcommunication method according to the present invention. FIG. 4 is anoperating sequence diagram of the multicast DSCH communication methodaccording to FIG. 3.

As described in FIG. 1, the reason why data can only be received by asingle mobile for a single transmission slot is that a mobile ID ispresent in the DSCH frame.

Consequently, according to the present invention, as shown in FIG. 3B,identification information (multicast ID) for multicast is stored in themobile ID storage area 306-2 of the DSCH frame 306 comprising the userdata storage area 306-1 and mobile identifier ID storage area 306-2.

In-this way, it is possible to arrange that a single DSCH frame 306 canbe simultaneously received by a plurality of mobiles 300 to 302. FIG. 3Ashows how a DSCH frame 306 using the aforesaid multicast ID issimultaneously received after reception of signaling data on theirrespective DPCHs by a plurality of mobiles 300 to 302.

The sequence during multicast communication using the DSCH described inFIG.3 will be further described using FIG. 4. When the wireless networkcontrol device 303 receives user data from the core network 100 (notshown in FIG. 3) (step S11), it determines whether this user data is tobe multicast or not; if this data is not to be multicast, it performsunicast processing in accordance with the sequence described in FIG. 2.

If the user data received from the core network 100 is to be multicast,the wireless network control device 303 generates the DSCH frame 306 ofFIG. 3B (processing step P11) from the information that was already setas the user data in question.

After this, the transmission timing of the DSCH frame 306 is determined(processing step P12). At this point, the multicast ID is stored in themulticast ID storage region 306-2 described in FIG. 3 in the DSCH frame306.

Next, based on the information relating to multicasting that is settherein, the wireless network control device 303 selects mobiles 300 to302 in respective of which multicasting is to be performed (processingstep P13) and determines (processing step P14) the transmission timingof the signaling frame and the generation of the signaling data for eachmobile that is the subject of this multicasting.

The respective signaling data are transmitted (step S12) to all themobiles 300 to 302 that are the subject of multicasting through the basestations 304, with the aforesaid signaling transmission timing. When themobiles receive this signaling, they recognize the presence of the DSCHframe that is to be received on PDSCH and commence preparations forreception of this DCSH frame (processing steps P14-1 to P14-3).

After this, the wireless network control device 303 transmits the DSCHframe through the base stations of 304 to the mobiles 300 to 302 withthe DSCH frame transmission timing. (step S13).

After the mobiles have all received the DSCH frame 306 transmitted asdescribed above, they check the mobile identifier ID in the respectivelyreceived data (processing step P15) and, if the identifier ID agreeswith the multicast ID, continue processing of this received data(processing step P16). If the ID is not a multicast ID, in theprocessing step P6 in the sequence of FIG. 2, the mobiles compare the IDwith their own IDs, respectively and, if they agree, perform thesubsequent data processing. Also, if the,ID in the received data andtheir own-ID do not agree, they discard the DSCH frame 306 (processingstep P7).

An embodiment of a wireless network control device 303 that executesthis processing in a sequence in accordance with the present inventionas described above will now be described.

FIG. 5 shows an embodiment of a wireless network control device 303according to the present invention.

The wireless network control device 303 comprises a DSCH processingsection 500, macro diversity processing section 505, main controlsection 507 and circuit terminating section 506; the respectivefunctional sections are connected by an internal bus 501.

The macro diversity processing section 505 is a functional section forimplementing macro diversity, which is a characteristic technique inmobile communication. In macro diversity, a plurality of channels areset up between a given node and a given mobile and identical data arecopied and transmitted to all of the plurality of channels by thetransmitting end. This is employed because communication quality such asduring handover is improved by selecting at the receiving end the dataof highest quality, of the identical data received on the plurality ofchannels.

Specifically, the macro diversity processing section 505 chieflyperforms the following two processes.

(1) The data destined for a given mobile received from the core network100 is copied to as many channels as are set up on the mobile inquestion, and transmission is performed to the mobile on all these setchannels.

(2) The respective qualities of the data received on the plurality ofchannels from a given mobile are evaluated and the data that afford thebest quality are selected and transmitted to the core network 100.

The circuit terminating section 506 has the function, of terminating allcircuits such as on the side of the core network 100 or on the side ofthe base stations 304 and of using the channel to transmit data to aprocessing block in a suitable device or another node.

Apart from setting the information of the various functional blockswithin the device, the main control section 507 has the function ofexchanging control information with other nodes.

The DSCH processing section 500 comprises a DSCH frame processingsection 504 that performs therein DSCH frame generation and transmissiontiming adjustment etc, a multicast setting table 502 that storesinformation relating to multicasting using DSCH, and a DSCH settingtable 503 that stores information for ordinary DSCH communication.

The control information received from the main control section 507 etcis set and stored in the multicast setting table 502 and/or the DSCHsetting table 503. This information that has thus been set and stored isreferenced during for example frame generation processing ortransmission timing determination by the DSCH frame processing section504.

It should be noted that, although, in the embodiment of FIG. 5, the DSCHprocessing section 500 and the macro diversity processing section 505were constituted as separate functional blocks, this DSCH processingsection 500 and macro diversity processing section 505 could besubstantially constituted by a single functional block.

FIG. 6 shows a practical example of a multicast setting table 502. Thelayout of the multicast setting table 502 is that a single row shows thesetting information of a single multicast group; this settinginformation comprises (a) a multicast channel identifier ID, (b) a DSCHidentifier ID, (c) the number of mobiles participating in this multicastgroup and (d) the identifier IDs of these mobiles.

The details of these respective items of setting information aredescribed below.

(a) “Multicast Channel Identifier ID”

This is the identifier of the multicast data distribution channel thatis set up between the wireless network control device 303 and the corenetwork 100. Although, in this case, it was assumed that a singlemulticast channel was always mapped onto a single DSCH, depending on thelayout of the table, it would be possible to map a single multicastchannel onto a plurality of DSCHs.

(b) “DSCH Identifier ID”

This is the identifier that is applied to a DSCH. In this case also, itis assumed that a single multicast channel is mapped onto a single DSCH,but, depending on the layout of the table, it would be possible to map aplurality of multicast channels onto a single DSCH.

(c) “Number of Mobiles”

This indicates the number of mobiles participating in a multicast groupin the DSCH indicated by the DSCH identifier ID.

(d) “Mobile Identifier IDs”

This is a list, having the same number of entries as the number ofmobiles, of the IDs that distinguish the mobiles that participate in themulticast-group.

FIG. 7 shows a practical example of the DSCH setting table 503. One rowof the layout of the DSCH setting table 503 indicates the settinginformation relating to a single DSCH; this setting informationcomprises: (a) the identifier ID of the dedicated channel, (b) a DSCHidentifier ID, (c) the identifier IDs of the mobiles corresponding tothe identifier ID of the dedicated channel, and (d) the timing offsetsin the signal transmission that is set up in respect of the mobiles.

The details of the respective items of setting information are describedbelow.

(a) “Identifier ID of the Dedicated Channel”

This is the identifier of the channel that is uniquely allocated to therespective mobiles and that is set up between the wireless networkcontrol device 303 and the core network 100. A single dedicated channelis always mapped onto a single DSCH.

(b) “DSCH Identifier ID”

This is the identifier that is applied to the DSCH. A single dedicatedchannel is mapped to a single DSCH.

(c) “Mobile Identifier IDs”

These are the identifier IDs of the mobiles to which the dedicatedchannel is allocated.

(d) “Timing Offset”

This expresses the amount of offset from the reference timing in thewireless network control device; transmission is effected to the mobileswith a timing that is adjusted by the amount of this offset from thisreference timing.

FIG. 8 and FIG. 9 are views indicating what information is set in themulticast setting table 502 and the DSCH setting table 503,respectively, corresponding to the specific example of system conditionshown in FIG. 10.

FIG. 10 shows only the wireless network control device 304; the basestations 304 are not shown. In this specific example, three DSCHs, #0 to#2 are set up; the multicast, channels MC_CH #0 and #1 and the dedicatedchannels CH #0 to #2 are accommodated on the DSCH #0; the multicastchannel MC_CH#2 and the dedicated channels CH #3 to #6 are accommodatedon the DSCH #1; and the dedicated channels CH #7 to #8 are accommodatedon the DSCH #2.

Furthermore, the mobiles #0 to #2 perform communication through the DSCH#0, the mobiles #0 and #2 are mobiles participating in multicasting,while the mobile #1 is a mobile that does not participate inmulticasting.

Also, the mobiles #3 to #5 perform communication through the DSCH #1and, of these, the mobiles #3 to #5 are mobiles participating inmulticasting while the mobile #6 is a mobile that does not participatein multicasting. Further, the mobiles #7, #8 perform communicationthrough the DSCH #2, but these mobiles do not participate inmulticasting.

In regard to the condition of FIG. 10, the multicast setting table 502of FIG. 8 has registered therein (a) which multicast channels are (b)accommodated on which DSCH and (c) the number of multicast participantmobiles and (d) the identifier IDs of the participant mobiles.

In contrast, the DSCH setting table 503 of FIG. 9 has registered therein(a) of the dedicated channel IDs, (b) the subject DSCH identifier IDsthat are accommodated therein, and (c) the corresponding mobileidentifier IDs.

FIG. 11 is a view showing the processing sequence from start-up of thesystem up to commencement of multicast communication.

When the mobile network i.e. the wireless network control device 303 andthe base stations 304 are started up, various settings are performed(processing step P21) in accordance with a predetermined procedure,between these nodes. At this point, setting of the DSCHs employed in thepresent invention is also performed (processing step P22).

When DSCH setting is completed, next, setting of the data channels formulticasting between the core network 100 and the wireless networkcontrol device 303 is performed (processing step P23). Although notshown in FIG. 11, it is assumed that the data channel for multicastingis connected for example to a data distribution server within the corenetwork 100 (processing step P24).

After set-up of the data channel for multicasting has been completed,the multicasting setting table 502 within the wireless network device isupdated (processing step P24) in accordance with the mapping informationof the data channels for multicasting that have been set up and theDSCHs.

After this, communication of the multicast data from for example thedata distribution server is commenced, (step S21). At this stage, thereneed not necessarily be any mobile that receives the multicast data.Alternatively, it is also possible to stop transmission of the multicastdata and to issue the data transmission commencement request to theserver at a time-point where the mobiles that are to receive themulticast data are registered.

After this, when call connection of a particular mobile is effected(processing step P25), and when, by a prescribed procedure, a changeoverdecision is made (processing step P26) to use DSCH, the wireless networkcontrol device adds this mobile to the DSCH setting table 503(processing step P27).

After this, instructions to change over to the DSCH are transmitted tothe mobile 300 in question via the base station 304 (step S22).

When the mobile 300 receives the instructions to change over to DSCH, itextracts and sets,the parameters for DSCH reception that are containedin the changeover instruction signal (processing step P28).

In addition, a decision is made as to whether or not the mobile 300 inquestion is to participate in the multicast transmission to which DSCHis being applied (processing step P29) and the mobile 300 in questionreturns (step S23) to the wireless network control device through thebase station a response message of completion of DSCH changeover,including the result of this decision.

Regarding this decision as to whether or not the mobile 300 is toparticipate in multicast communication, the methods may be considered ofsetting the result of this decision before hand by the user in themobile or of setting the result of this decision in the network.

When the wireless network control device 303 receives from the mobile300 the DSCH changeover response, if this contains a request toparticipate in multicasting, it updates the multicast setting table 502therein to add the mobile in question (processing step P30).

It should be noted that, if, as the method whereby it is decided whetheror not the aforesaid mobile is to participate in multicastcommunication, the method is adopted of setting the result of thisdecision in the network, authentication processing may be performed inthe network 100 in the event of reception of a DSCH changeover responsefrom the mobile, if the mobile is to participate in the multicastcommunication, processing may be performed to add the mobile to themulticast setting table 502.

After the mobile has been added to the multicast setting table 502, datais distributed (step S24) from the server or the like. This distributiondata is assembled into DSCH frames in the DSCH processing section 500 inthe wireless network control device 303 and its transmission timing isdetermined (processing step P31). After this, signaling in respect ofthe added mobile (step S25) and transmission of the DSCH frame (step 26)are performed.

For its part, after the mobile has received the signaling that has beentransmitted thereto by the wireless network control device 303, DSCHreception processing (processing step P32) is initiated. DSCH framereception processing (processing step P33) is performed as describedwith reference to FIG. 2 (processing steps P6 and P7) and FIG. 4(processing steps P15, P16).

FIG. 12 shows a specific example of a method of signaling. Signalingmust be transmitted to each mobile, so channels for signalingtransmission must be set up allocated in units of the number of mobiles.

In 3GPP, as the channels for signaling, two methods are laid down,namely, a method employing a DCH and a method of setting up a newchannel. (signaling bearer) for signaling. Referring to FIG. 12, adescription will now be given as to how signaling is actuallytransmitted within the wireless network control device 303 in the abovetwo cases.

As described above, since signaling is generated and transmitted whendata is transmitted on the DSCH, the opportunity for signalingtransmission is created by the DSCH processing section 500.

This will be described with reference to the following four cases.

[Case A]

The case A shown in FIG. 12A is a case in which signaling is transmittedwith DCH. In accordance with the embodiment described in FIG.5, the DCHis terminated by the macro diversity processing section 505, so in theevent of signaling transmission the DSCH processing section 500 mustoutput a signaling transmission instruction to the macro diversityprocessing section 505.

At this juncture, the macro diversity processing section 505 must beable to identify in respect of which mobile (DCH) signaling is beingtransmitted, so the DSCH processing section 500 must give instructionsfor signaling transmission to the macro diversity processing section 505and hand over the identifier ID of the mobile that is the subject ofthis transmission. At this juncture, in order for the transmissioninstruction and mobile identifier ID to be exchanged between the DSCHprocessing section 500 and the macro diversity processing section 505,the method of FIG. 5 of employing an internal bus or the method ofproviding a dedicated control path for signal exchange may beconsidered.

The macro diversity processing section 505 generates signaling data fromthe signaling transmission instruction and mobile identifier ID receivedfrom the DSCH processing section 500 and transmits this signaling dataon the corresponding DCH. Although not shown in FIG. 5, the macrodiversity processing section 505 is internally provided with mappingtable means of the mobile identifier ID and DCH.

[Case B]

Case B, shown in FIG. 12B, is also a case in which signaling istransmitted with DCH. Unlike the case of FIG. 12A, it has acharacteristic feature in regard to the method whereby generation andtransmission of the signaling data are performed by the DSCH processingsection 500 and mapping of the signaling data onto the DCH is performedby the circuit terminating section 506.

The DSCH processing section 500 performs transmission of signaling datato the circuit terminating section 506 using the same channel ID as thechannel of the DCH where the macro diversity processing section 505terminates. The channel ID whereby signaling transmission was performedby the DSCH processing section 500 is the same as the ID of the DCHcorresponding to the mobile that is to receive the signaling, so thesignaling data is merged with the DCH in the circuit terminating section506 before being transmitted to the corresponding mobile through thebase station 304.

It should be noted that, in this case, the DSCH processing section 500must simultaneously identify the channel ID of the DCH corresponding tothe mobile that is registered. This can be achieved by storing asadditional information in the DSCH setting table 503 shown in FIG. 7.

[Case C]

In case C shown in FIG. 12C, a channel for signaling (signaling bearer)is newly set up between the DSCH processing section 500 and base station304. This is an example in which signaling data is transmitted usingthis channel. In this case, the signaling data that is generated in theDSCH processing section 500 is transmitted by the signaling bearer atwhich the DSCH processing section 500 terminates, without modification.

[Case D]

In the case D shown in FIG. 12D, a channel for signaling (signalingbearer) is newly set up between the macro diversity processing section505 and the base station 304; this is an example of the case wheresignaling data is transmitted using this channel. This case also is thesame as case A.

FIG. 13 is a view showing the processing flow during DSCH transmissionin the wireless network control device 303, in particular in the DSCHprocessing section 500 and the macro diversity processing section 505.In this case, case A of FIG. 12A is employed as the signaling method.

When the DSCH processing section 500 receives data from the core network100 (processing step P40, Yes), the channel ID of the received data isextracted (processing step P41). The DSCH processing section 500 checksfor the existence of the channel ID extracted in the processing step P41in the multicast setting table 502 (processing step P42) by referencingthis multicast setting table 502.

If the channel ID extracted in the processing step P41 is present in themulticast setting table 502 (processing step P42, Yes), the DSCHprocessing section 500 extracts the DSCH-ID and all of the mobile IDsbelonging to the DSCH from the multicast setting table 502 (processingstep P44).

Next, if not even one mobile ID is present in the multicast settingtable 502 (processing step P45, No), nor in the DSCH setting table 503(processing step P43, No), the data is discarded (processing step P46).

If one or more mobile ID is present in the multicast setting table 502(processing step P45, Yes) the DSCH processing section 500 applies thedata received in processing step P1 to the multicast ID to generate theDSCH frame (processing step P47).

On the other hand, if, in processing step P42, the channel ID extractedin processing step P41 is not present in the multicast setting table 502(processing step P42, No), the DSCH processing section 500 checks toascertain whether or not the extracted channel ID is present in the DSCHsetting table 503 (processing step P48).

If, in processing step P48, the extracted channel ID is not present inthe DSCH setting table 503, the DSCH processing section 500 discards thedata received in the processing step P40 (processing step P49).

If, in the processing step P49, the extracted channel ID is present inthe DSCH setting table 503 (processing step P48, Yes), the DSCHprocessing section 500 extracts the DSCH-ID and mobile ID from the DSCHsetting table 503 (processing step P50). After this, the extractedmobile ID is applied to the data received in the processing step P1 andthe DSCH frame is generated (processing step P51).

Next, after the DSCH frame has been generated in the processing stepsP47, P51, the DSCH processing section 500 determines the transmissiontiming of the DSCH frame that has been generated (processing step P52)and acquires the timing offset of the mobile corresponding to this DSCHfrom the DSCH setting table 503 (processing step P53).

In this way, the signaling data transmission timing is calculated(processing step P54) from the DSCH frame transmission timing and thetiming offset of the mobile.

After this the DSCH processing section 500 reports the mobile ID and thesignaling transmission instruction to the macro diversity processingsection 505 (processing step P55) in accordance with the signalingtiming determined in processing step P54.

The macro diversity processing section 505 generates a signaling frameusing the mobile ID and the signaling transmission instruction that arehanded over from the DSCH processing section 500, and transmits thissignaling frame on, the corresponding DCH (processing step P56,).

The processing of the aforesaid steps P52 to P56 is executed a number oftimes equal to the number of mobiles. After this, the DSCH processingsection 500 transmits (processing step P57) the DSCH frame generated inthe processing step P47 or in the processing step P51 on the DSCH inaccordance with the DSCH frame transmission timing that was determinedin the processing step P52.

FIG. 14 is a view showing the processing flow during DSCH reception by amobile. In FIG. 14, it is assumed that the dedicated channels (DCH,DPCH) are already set up by a prescribed procedure at the mobile.

When the mobile receives signaling on the DPCH (processing step P60,Yes)), the DSCH reception preparation is commenced (processing step P61)and the DSCH frame on the PDSCH is received (processing step P62).

After this, an error check of the DSCH frame is performed (processingstep P63). If any abnormality in the data is found, the received DSCHframe is discarded (processing step P64).

If the received DSCH frame is normal (processing step P63, Yes), theidentifier ID in the DSCH frame is checked (processing step P65) and ifthis identifier ID is a multicast ID (processing step P66, Yes), dataprocessing as multicast data is performed (processing step P67).

On the other hand, if, in processing step P66, it is found that theidentifier ID is not a multicast ID, the identifier ID in the DSCH frameis compared with the mobile's own identifier ID (processing step P68)and if it is not found to agree with the mobile's own identifier ID(processing step P68, No), the received DSCH frame is discarded(processing step P64).

If the identifier ID agrees with the mobile's own identifier ID(processing step P68, Yes), ordinary unicast processing is performed(processing step P67).

FIG. 15 describes the operation when a control frame is received fromthe base station 304. In 3GPP, various control frames are definedbetween the wireless network control device 303 and base station 304.One of these is a control frame called the timing adjustment controlframe. This is employed to adjust the channel timing that is set betweenthe wireless network control device and the base station.

The timing adjustment control frame is used to store and transmit thedifference with respect to the appropriate reception timing from thebase station 304 to the wireless network control device 303, in caseswhere the data that was transmitted by the wireless network 100 is notreceived with the appropriate timing at the base station 304. Also, thetiming adjustment control frame is returned using a channel where thetransmission timing is abnormal.

When the wireless network control device 303 receives a timingadjustment control frame, it adjusts the transmission timing within thewireless network control device 303 by the amount of the timing too beadjusted that is stored in the frame relating to the received channeland subsequently performs data transmission with this timing.

The details of timing adjustment are set out in 3GPP TS25.402.

In a data communication system using DSCH, the signaling data istransmitted to the mobile immediately prior to transmission of the DSCHframe, but, as mentioned 15 above, the transmission timing of thesignaling data is based on the transmission timing of the dedicatedchannel (DCH, DPCH)

Consequently, if any abnormality were to be generated in thetransmission timing in the dedicated channel during transmission on theordinary dedicated channel, in regard to this dedicated channel, in theevent of an incoming transmission of this timing adjustment controlframe it would not only be necessary to adjust the transmission timingof this dedicated channel, but it would also be necessary to adjust thetiming offset of each mobile stored in the DSCH setting table 503 in theDSCH processing section 500.

Accordingly, as described above, when a timing adjustment control frameis generated on a dedicated channel, the method is specified ofreporting the control information (in this case, the timing adjustmentvalue) also to the DSCH processing section 500. It should be noted thatthe following method can likewise be applied to other control framesassociated with the dedicated channel.

FIG. 15A to FIG. 15C show three patterns, namely, case A, case B andcase C as methods for reporting control information on reception of atiming adjustment control frame to the DSCH processing section 500.These three patterns will be described below.

[Case A]

In Case A shown in FIG. 15A, the timing adjustment control frame that istransmitted on the DCH is terminated by the macro, diversity controlsection 505, and an adjustment value in respect of the DCH is extractedfrom the control frame.

The macro diversity processing section 505 performs timing adjustment ofthe DCH in question within its own processing section, using the aforesaid adjustment value. The macro diversity processing section 505reports this adjustment value and the mobile ID to the DSCH processingsection 500. The DSCH processing section 500 is thereby able to adjustthe timing offset amount corresponding to the mobile in question in theDSCH setting table 503, using the adjustment value and the mobile ID.

[Case B]

In case B shown in FIG. 15B, the circuit terminating section 506 copiesall of the up link data that is transmitted on the dedicated channelterminated by the macro diversity processing section 505 and transmitsthis also to the DSCH processing section 500.

The DSCH processing section 500 is arranged to monitor, all the time,the uplink data on the dedicated channels that are received bytransmission from the circuit terminating section 506 so as to receiveonly control data such as timing adjustment frames and discard ordinaryuser data. In this way, the DSCH processing section 500 can also learnthe timing adjustment amount on the dedicated channels.

[Case C]

In Case C shown in FIG. 15C, a number of control frame dedicatedchannels equal to the number of dedicated channels are set up betweenthe wireless network control device 303 and the base stations 304 andcontrol frames are transmitted to the wireless network control ,device303 from the base stations 304 on the dedicated channels. In thisprocess, respective copied control frames are transmitted on thededicated channel in question and the control frame dedicated,channel inquestion after copying the control frame within the base station 304.

Service employing multicast DSCH that is capable of being implemented byapplying the present invention will now be described.

As described above, in order for the mobile to receive data on DSCH, itis essential to receive signaling data on a dedicated channel (DPCH)

This means that, in order to receive DSCH, the mobile must be incall-connected condition rather than in idle condition. Specifically, acharacteristic feature of service using multicast DSCH is that a servicecan be provided that is distributed by multicasting to mobiles that arein connected condition.

Also, although description thereof has been omitted from the above, oneor several DSCH channels are normally set up for each area unit andchangeover of the DSCH that is being received is performed when a mobilemoves from, a given area to another area. In other words, this may besaid to constitute a further characteristic feature of multicastcommunication using DSCH in that different information can bedistributed for different areas.

Thus the characteristic features of a multicasting service using DSCHmay be summarized as “an area-aware service available only to mobilesthat are in a call-connected condition”.

It should be noted that, since DSCH cannot be received by mobiles thatare not in a call-connected condition, there is no wasted powerconsumption due to multicast distribution to mobiles that are in an idlecondition.

Various examples of such services are described below.

[Practical example l: area information distribution service usingmulticast DSCH]

Information relating to this area is constantly distributed usingmulticast DSCH, for each area, from for example server means within thecore network, and the mobile receives this area distribution informationby performing call connection.

[Practical example 2: BGM distribution service using multicast DSCH]

For example music data is constantly transmitted from for example servermeans in the core network and this is multicast within the area usingDSCH. When a mobile comes into service by performing call connection,this distributed music data is received on the DSCH and reproduced. Inthis way, it is possible to hear as BGM this music that is received inthe background, while carrying on a conversation with another party.

Furthermore, it may-be envisioned that a service may be provideddisplaying characteristic features for each geographical region by usingdifferent music data for each area. This is of course not restricted tomusic data and a similar service could be provided for all types ofaudible data.

INDUSTRIAL APPLICABILITY

There has been an enormous increase in communication rates andcommunication quality in recent years due to advances in mobilecommunication technology. As a result, service modes have beendiversified and services are being commenced that handle largequantities of data in the form not merely of voice telephone service butalso of images or video. Currently however, most services are userrequest type services and high rate broadcast/multicast type servicessuch as radio or television are considered merely as futurepossibilities.

Viewed from this aspect, as mentioned above, the currentthird-generation mobile communication technology, inparticular, W-CDMAcommunication networks as specified by 3GPP, are not considered toprovide an optimum method for realizing high rate multicast services inan efficient manner at the present time. This must have the effect ofimpeding the development of communications services which might beexpected to offer high diversity in, the future.

With the present invention, efficient multicast services can beimplemented simply by revising somewhat the DSCH technology in, 3GPP.Also, by exploitation of the highly characteristic technical featurethat “a distributed service allocated in area units can only be receivedduring call connection”, it is envisioned that various different typesof services, which were hitherto difficult to implement, may be expectedto become: further developed, leading to expansion of the mobilecommunication market.

Furthermore, it is envisioned that such diversification and expansion ofservices will make it possible to change over from a situation in whichcommunication enterprises obtain profit by communication charges fromusers towards a situation in which communication network charges areobtained from multicast service providers, thereby making it possible toreduce communication charges that are currently borne by users, and as aresult make it possible to further expand the market.

1. A system for mobile communication comprising: a base stationcomprising: a first transmitting unit operable to transmit to a mobilestation, identifying information for multicast data to be to the mobilestation, and a second transmitting unit operable to transmit the data ona shared channel to the mobile station, wherein the data is identifiedby the information transmitted; and a mobile station comprising: a firstreceiving unit operable to receive from the base station identifyinginformation for the multicast data, and a second receiving unit operableto receive the data on the shared channel from the base station, by theinformation received.
 2. The system of claim 1, wherein the sharedchannel is same channel among a plurality of mobile stations.
 3. Thesystem of claim 1, wherein at least a portion of the data transmitted onthe shared channel is for a plurality of mobile stations.